The present invention relates to slider needles for warp knitting machines, and in particular, relates to a slider needle having a slider provided with a cam to perform the function of a conventional trick plate.
In the prior art, warp knitting machines conventionally utilized a trick plate and associated guides to lay in a trick plate thread. These guides are affixed to a guide bar and move up and down simulating trick plate action. Typical of these is German patent OLS No. 1,585,511. As the thread guide pass between the needles, the slider of the needle is fully opened permitting the thread to enter the opening of the needle. The guides must swing alongside the needle, approximately at the level of the hook portion, in order to lay the appropriate thread into the hook opening. They are moved out of the hook opening by the downward movement of the thread guides so that the thread slides on to the needle shaft. The threads as they are moved out of the needle openings should become positioned under the cam on the slider, which is positioned near the tip thereof, so that the slider is in a position to move the thread in a downwardly direction as the slider moves in that direction. The position of this cam at the very top of the slider makes it more difficult to form the ground stitch, since the trick plate thread may remain stuck within the hook opening. Also, it is necessary to provide a further suspension means with steering to accomplish the trick plate-like movement of the thread guides.
Another machine, known in the prior art, wherein the guides perform a trick plate-like movement is Japanese Utility Model No. 39-19271. However, the disclosure in this patent uses compound or tubular needles which are not readily adaptable to include a cam mechanism.
The present invention overcomes the shortcomings found in the prior art by utilizing a different location for the cam and/or modification of the needle shank. In the preferred embodiment of the present invention, when the guides carrying the trick plate threads swing through the spaces between the needles in the forward direction, the hook openings of the needles are partially or entirely closed by the slider mechanism.
The cam on the slider is positioned below the top of the slider proximate the area where the slider leaves the shank of the needle. Using this configuration, only one suspension system is required for all the guides, since the hook openings of the needles are protected against the entry thereinto of the trick plate threads. Therefore, the guides of the trick plate threads can, like the other ground thread guides, swing through at the same height as the needle hook opening without requiring an additional movement. Furthermore, the formation of the regular stitches can continue as before, since the height of the closure of the slider remains as usual.
In a warp knitting machine, according to the principles of the present invention, there are provided at least two guide bars, a needle bar having a plurality of slider needles thereon, and cooperating driving means, one of the guide bars is provided with a plurality of guides for laying in ground threads and the other guide bar is provided with a plurality of guides for laying in trick plate threads. In the present machine each slider needle comprises a hook formed end portion and a shank portion having a slot provided therein. A slider member is disposed in the slot and slidably cooperates therewith. Each slider has one end portion thereof extending from the shank portion across the mouth of the opening of the hook portion acting to close the mouth in a first position and acting to open the mouth in a second position. The slider member end portion has a narrow tip portion adapted to cooperate with the tip of the hook formed end and an enlarged cam portion displaced away from the tip portion and disposed within the mouth of the opening in the first position. The other end portion of the slider member is adapted to be coupled to the driving means for movement from said first to said second position.